Woven-fabric test piece and method of testing woven fabric



Patent-sang. 19, 1924.

YUNITI-:o STATES PATENT oFFlcE.

EIABAH D. AYRES, OF AKRON, OHIO, ASSIGNOB TO THE B. F. GOODBICH CUHPANY, Ol NEW YORK, N. Y., A CORPORATION OF NEW YORK.

WOVEN-FABRIC TEST PIECE AND IETHOD Ol' TESTING WOVEN FABRIC.

Application led February 9, 1980. Serial No. 357,315.A

To all whom it may concern.:

Be it known that I, HTRAM D. Arms, a citizen of the United States, residin at Akron. in the county of Summit and tate 6 of Ohio` have invented a certain new and useful Woven-Fabric Test Piece and Methods of Testing Woven Fabric, of which the following is a specification. y

This invention relates to the art of testing woven fabric such as that used for making pneumatic tires or that used for making balloon envelopes, which fabric as it comes from the loom is often or usually in an unbalanced conditionas res ects the amount of crimp in the warp and ller, respectively, and hence lacks a maximum degree of suitability for its intended purpose. The object of my invention is to provide an improved form of fabric test-piece, an improved method of preparing and an improved method of using the same, for the purpose of determining the characteristics of the fabric in one or more of its various stages,- for example, in its uncoated conditionas it comes from the loom, in its rubberized condition before application to purposes such as tire making, and in its condition after use in the tire or other article. This determination affords information to the manufacturer of articles made from the fabric, such as tires, which permits the intelligent applicationof expedlents, either during or after the weaving of the fabric, tending to correct the usual inequalities, The principal inequality commonly found in tire fabric, for instance, consists in a greater degre of crimp in the warp threads than exists in the weft or filler threads, owing to the methods used in weaving, so that when the two sets of threads are subjected to equal elongations in an inflated tire, the warp threads, being more stretchable than the filler threads, are subjected to a less degree of strain.

The accompanying drawing shows in elevation, partly broken away, a test-piece of fabric prepared and mounted according to my invention, together with the grips through which the desired loading is applied to the two sets of threads.

This test-piece is made in the shape of a Greek cross, with four arms 10, 10 of approximately equal length, and a central quadrilateral 11, which for convenience may be termed a squa-re, although the two sets of threads in the fabric when taken from a pneumatic tire, for example, are often at an angle to each other otherthan a right-angle. The cross-shaped test-piece is detached from a. sheet of woven fabrlc by cutting the arms, at their sides, (parallel to the longitudinal threads of sai arms, and at their ends,

across said lon 'tudinal threads, and some Y of the interme iate cross threads are then drawn for a purpose to be described. In testing this fa ric piece I prefer to hang it in a vertical plane with the band of warp threads 12 running vertically and the band of ller threads 13 horizontally, or at a slight angle to the horizontal if the piece to be tested is taken from a portion of a structure such as a tire, where the two sets of threads lie lat other than a right-angle to each other.

14, 14 are grips or clamps, four in number, applied to the ends of the arms of the fabric test-piece, and each comprising a pair of stout plates or dat bars 15, held against the fabric by bolts 16 and roughened on their inner surfaces as indicated at 17 in order t0 increase their hold upon the fabric. To the members of each pair of grips 14 oppositely-pulling forces are applied by means of draw-bars 18, whose inner ends are represented in the drawing lying between the plates of the grips and engaging their middle portions by means of pins 19, this middle point of application of the pulling forces being especially desirable when testing non-rectangular fabric taken from a tire. The elongation of the warp or filler threads, or both, due to the loading forces,

is observed by making suitable marks on the fabric and noting their increment of length or amount of shifting of position as the loads are increased. The loadin forces may be of any suitable character suc asv weighted cords or chains passing over pulleys, and the application of the welghts and observation of measurements on the fabric testpiece may be performed in any suitable' way.

The portions of the fabric test-piece e11- gaged by the grips 14 contain both sets of threads in order to retain the proper form of such portions and increase the adhesion of the grips upon the lon 'tudinal threads which are being subjecte to strain. Between the gri s and the central test-square 11 the crosst reads in each arm 10 are removed or drawn.' Heretofore, in the testing' enabled to obtain of fabric by means of cross-shaped testpieces to v vhose arms various loads are a plied, the cross threads have been left 1n the arms between the 'ps and the central square and the effect as been to contract the width of said arms owin to the increasing crimp of the crossreads when tension is ap lied to the longitudinal threads, with 51e consequence that uncertain readings of elongation are obtained in the central test-square, the corners of this square are over-strained and the fabric threads break at these corners before the limit of strength of the 'middle is reached.

en the cross threads are drawn in accordance with my invention these troubles are obviated.

The fabric test-piece when strained to the limit of strength of its threads should theoretically brea yin the woven central uare 11 rather than in the unwoven th the arms 10,\for the reason that the straight threads in these arms are subjected to a force only equal to the longitudinal force acting in the plane of the fabric, whereas the crimped threads in the central square are subjected to resultant forces acting at an a'ngle to the plane of the fabric a ong the sides of the waves or undulations form the crimps, which forces are greater than the force acting in the plane of the fabric. Experience confirms theory, as it is found that the threads will break in the majority of cases in the woven fabric of the central square.

It will be obvious from the description thus far given that I have devised a form of fabric test-piece and a mode of using the same by which the manufacturer of arti' cles such as tires made from the fabric is useful information as to the characteristics of such fabric which will, if desired, enable corrections to be made improving its quality either in the weavin of the same or in the treatment of the fa ric after it is woven. For example, if by applyi ual loads to the warp and filler threz's o the tes`t-piece it is found that the warp threads stretch a certain percentage more than the filler threads, or if by imposing equal amounts of elongation u n the wa and filler threads it is found t at a certain less increment of weight is requiredfto impose this elongation ion the warp threads than is required for e filler threads, the user of mly invention will know that a correspondin greater amount of crimp exists in the lier than in the warp. It is found in practice'that the amount of unbalance of the fabric in this respect varies greatly according to the particular mill from which the product comes, and as it is usually to the tire-manufacturers advan to buy his fabric from various sou it is de- Sirable for him to be able to treat the fabric ofl from these different sources in auch manner as to b it all to a condition of uniform or known egree of balance. This can 0 0n veniently be done in connection with the operation of apply' the coa of rubber to the fabric in a ca ender, and prefer to perform it b means of the automatic fabrictensioning evice form' the subject-matter of an application, 1grid No. 857,814, filed concurrently herewith. It may, on the other hand, be poible to obtain a balance of extensibility between the warp and the filler in the course of building the pneumatic tire casing, although this would be somewhat diiiicult. Even if noth' is done toward obtaining invention may afford the tire manufacturer information useful to him in connection with the acceptance or rejection of fabric or in the com of fabric from di'emnt rtiona of the same roll nkvlvlhch vary in their characteristics, in m up tire carcasses coinposed of several plies or liminations.

In the operation of my invention, the application of loads upon the fabric test-piece and the taking of of elongation in the central testuare may be done according to various sglans of procedure, which can largely be eft to the jud skill of the operator. The m e which I prefer, but which can be varied as circumstances or choice may demand, is to first lay out the fabric test-piece fiat upon a smooth surface and mark horizontal and vertical lines of predetermined length near the two edges thereof. Adjacent to these ent and lines two steel rules uated in small dimensions are attach to the fabric, one end of each rule having a fixed attachment and the other being su rted in such manner that the fabric may s 'de with respect to the rule so that the amount of increase in length of the marked lines along the warp or the filler can be observed inst the graduations on the rule, the ings bein preferably taken by two observers throug microscopes on opposite sides of the test-piece wlhen thlenlatiter is spefanlcled in a vertical pane. pacing e aricinthe the portions of the arms 10 e bgynie 'fips are somewhat stretched laterally as incatedinfulllinesinthedra ,sothat when the warp and filler are ed nearlytothebre 'gpoinggivingthetestpiece approximate y the outline shownb theiaettedlinesminhedra ,therewill not too great a opal-ture m parallelism in the threads of said arms as between those in the middle and those at the sides of the arms. In the method of equal elo tions, the eort is made to apply the l very nearly simultaneously upon the warp and filler threads respective degrees as will maintain 1n such their elongations the same. For example,

after applying a small minimum load, such as ve pounds, to the warp 12, balancing this with a co-ordinate load on the filler, and observing and recording the elongations corresponding to this first load on each set of threads, I then prefer to load the filler by successive predetermined amounts, such as 25, 50, 100, 200, etc., pounds, bringing the warp as nearly as possible simultaneously to an elongation equal to that caused by the filler load, noting this elongation and also the amount of the ller load and then proceed to the next loading, and soon until the fabric test-piece breaks. The recordedobservations may afterwards be plotted in the form of a curve or curves, if it is desired to display the results graphically, and a study of these results enables the tire-maker to apply the necessary corrections to the fabric or otherwise usefully to employ the infomation obtained, as already pointed out.

The details of procedure may, of course, be considerably varied without departing from my invention.

I claim:

1. A woven-fabric test-piece in the form of a cross with free ends, having the transverse threads Withdrawn from its arms adjacent to the central quadrilateral.

2. A woven-fabric test-piece in the form of a cross with free ends, the arms of said cross adjacent to the central quadrilateral having their transverse threads withdrawn, and said arms adjacent to their ends having the transverse threads in place.

3. A woven-fabric test-piece in the form of a cross having a substantially equal number of warp and filler threads, said cross having arms with free ends, the portions of said arms adjacent to the central square being free from transverse threads.

4. The method of preparing a wovenfabric test-piece which comprises detaching from a sheet of fabric a piece in the form of a Greek cross, with the warp and filler threads parallel to the arms of the cross and substantiall equal in number in both sets, and wit drawing the transverse threads from the arms adjacent to the cen tral square.

5. The method of testing woven fabric for characteristics of warp and filler which comprises preparing a cross-shaped testpiece with warp and filler threads running longitudinally of the respective arms and having the transverse threads withdrawn from said arms adjacent to the central quadrilateral, loading one of said sets of threads in a definite manner and observing the resulting elongation.

6. The method of testing woven fabric for characteristics of warp and filler which comprises preparing a cross-shaped testpiece having warp and filler threads running longitudinally of the respective arms, applying a known load to one set of threads, applying such a load to the threads of the other set as to elongate the latter by substantially the same amount as the first set, and observing the amount of the last-said load.

7. The method of testing woven fabric for characteristics of warp and filler which comprises preparing a cross-shaped testpiece having a substantially equal number of warp and filler threads running longitudinally of the respective arms, withdrawing the transverse threads from the four arms in zones between the outer end portions of said arms and the central square, applying grips to said outer end portions, applying a series of known weights through one pair of grips to the threads of one set and observing the resulting elongations of a measured portion of one of said threads in the central square, applying such weights through the other pair of grips to the threads of the other set as will cause successive elongations of an equal measured portion of one of the threads of the other set in said square substantially equal to the respective elongations of the first set, and observing the amounts of the several weights thus applied to said second set.

In testimony whereof I have hereunto set my hand this 5th day of Februa 1920.

HIRAM D. A ES. 

